Methods and apparatus for completing earth formations



SAHCH @OOM Oct. 19, 1965 c P LANMON u METHODS AND APPARATUS FOR COMPLETING EARTH FORMATIONS Filed Aug. 28. 1962 C /D ammo/7, l?

INVENTOR.

ATTORNEY United States Patent O 3,212,576 METHODS AND APPARATUS FOR COMPLETING EARTH FGRMATIONS C P Lanmon 1I, Friendswood, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Aug. 28, 1962, Ser. No. 219,969 8 Claims. (Cl. 166-23) This invention relates to methods and apparatus for completing oil wells and, more particularly, to methods and apparatus for selectively completing unconsolidated earth formations.

With new and improved investigating techniques in subsurface exploration for oil in the oil industry, it has become possible to identify the boundaries of productive formations with considerable accuracy so that, for example, a productive formation with a thickness of, say, 6 may be located and opened for production. It has now been determined that, in certain instances, only a few good perforations are necessary for economical production. In fact, in many instances, only a single perforation is required to produce the formation. Of course, in extremely thin intervals of formation, there is only space enough for one perforation. A common problem found in many of the oi-l and gas formations opened by perforations is that the formations are so unconsolidated that, in production, the flowing fluids produce sand; that is, particles of sand from the formations are produced with the fluid. In the well bore, the sand may settle out so as to eventually lill up the well bore or may be carried to the surface with the fluid where its effect on production equipment is quite deleterious.

To solve this problem, treating fluidskwhichpgpwsolidate the fogmmation sand have'beereveloped. A typical exanpiwo'f a treating fluid is a thermosetting sand consolidation plastic which contains formalin, a meta-paracresol mixture and guanidine carbonate. To use such a cementation agent, however, it is desirable to wash the perforation before introducing the cementation agent and following cementation it is desirable to flush the perforation with a washing iluid. To obtain a proper action, the fluids should be kept separated from one another and the formations should be properly controlled so that the sand is relatively undisturbed before treating. Following sand cementations, it is desirable to protect the perforation from mud damage.

It is accordingly an object of the present invention to provide new and improved methods and apparatus for completing 'oil wells with a treating fluid applied locally to the formation while controlling the condition of the formation sands.

In accordance with the present invention, the method includes the step of isolating a section of a well bore from borehole fluid, the step of perforating the isolated section of the well bore while maintaining pressure on the isolated section; and the step of introducing one or more treating agents into the isolated pressurized perforation in separated stages. After treating the formation, the perforation is temporarily plugged until the borehole fluid is removed from the well bore.

Apparatus of the present invention includes a well tool with means for isolating a selected portion of a well bore, means for perforating the isolated portion and means for simultaneously providing fluid under pressure to the isolated portion. Means are provided for determining the completion of the treating operation and for temporarily plugging the perforation.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner 3,212,576 Patented Oct. 19, 1965 of operation, together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross section of a cased borehole wherein the apparatus by which the present invention is practiced is shown schematically in cross section;

FIG. 2 is a view in cross section of the apparatus of the present invention; and

FIG. 3 is a view in cross section of a detail of the apparatus shown in FIG. 1.

Referring now to FIG. 1, a borehole 1li traversing the various earth formations 11 receives a casing 12 which is suitably secured therein by a column of cement 13 between the casing and the borehole. In the casing 12, prior to the production of the well, is a well control fluid 14, such as mud, which is calculated to be at a higher pressure than the pressures expected to result from the opening of the formations 11 to the casing so that the formation fluids are under control at all times.

A well completion tool 15 is adapted to be suspended in the casing 12 by means of cable 16 spooled on a winch (not shown) in a customary manner. Fluid discharge means 17 and a back-off shoe 18 are positioned on opposite sides of the elongated tool body and arranged to move relative to one another between a contracted and extended position. To accomplish the relative movement, the back-off shoe 18 is connected to piston rods and pistons 19 which are received in hydraulic cylinders 20 (only one being shown in the tool body). Tension springs 21 are provided for facilitating the retraction of the back-off shoe 1d from the wall of the casing 12 toward the tool body at the completion of the operation. An exemplary hydraulic actuating system 22 for the cylinders 20 may be of the type illustrated in the Chambers Patent No. 2,674,313.

In the upper end of the tool 15, other devices such as radioactivity responsive instruments of various types may be employed to obtain logs of the formations so that the tool assembly may log the formation and, while still in the hole, a productive zone may be located and the perforator employed to open the formations.

As shown in FIGS. 1 and 2, the fluid passage means 17 includes an explosive chamber 23 in which a shaped charge 24 is received. A face plate member 25 (FIG. 2) is received in the explosive chamber 23 to mount the explosive charge 24 therein. The face plate member 25 has a forward bulb-like extension 26a and an annular resilient sealing pad 27a is attached to the face plate about the bulb-like portions 26a The face plate member 25 has an outer annular groove 26 which is connected by radial bores 27 to a central bore 28. In the central bore 28, to either side of the open ends of bores 27 are frangible closure members 29, 31B. The closure member 29 prevents fluids within the central bore 28 and fluids exterior of the housing from intermixing while the closure member 30 prevents fluids in the central bore 28 from coming in contact with the explosive charge 24. A passageway 31 opening to the annular groove 26 of the face plate member is connected to a normally closed valve 32 schematically shown in FIG. 2 which, when opened, admits well fluid to the passageway 31 for purposes which will hereinafter become more fully apparent.

As shown in FIG. l, another passageway 33 in the tool connects the annular groove 26 to a normally closed valve 34 and a normally open valve 35. A pressure sensing device 36, which may be any conventional type of pressure transducer or of the type illustrated in FIG. 9 of the Desbrandes Patent No. 3,011,554, is connected to passageway 33 for determining pressure in the passage- Way and transmitting a characteristic electrical signal via a conductor in cable 16 to the surface. The normally open valve 35 is connected by a central passageway 37 to a fluid treating cylinder 3S which is separated into three chambers 39, 4t), 41 by spaced, movable, piston members 42, 43, 44. The upper f :harrlulger contains a pre -fl`ush fluid such as a saliresb'lution the intgrrnediate chamber coptuains a plastic consolidatmivopfluid such as a formalinecresl"nixturewhile the loweg/chamber contains an after flush fluid su'ch as kerosine. The lower chamber 41 i'srfr'n'edb'tveeii"the piston member 43 and piston member 44, the cylinder 3S below the piston member 44 'being opened by a port 45 to the well fluid 14. In a manner which will hereinafter become more apparent, the Well fluid 14 acting on the lower piston member 44 exerts pressure on the fluids in the chambers 39-41 which discharges the fluids in the chambers into the passageway 37 into the formations in sequence.

The normally closed valve 34 is connected by a conduit 46 to an annular chamber 47 formed between a cylindrical wall surface of the housing and the tubular passageway 37 to the treating cylinder 38. Chamber 47 contains a plugging fluid such as Black Magic oil base mud as supplied by Oil Base, Inc. of Campton, California. The lower end of chamber 47 is provided with a port 49 and intermediate of the port and plugging fluid is a piston 50. Well fluid 14 thus can act upon the piston 50.

Referring now to FIG. 3, the piston members 42, 43 are illustrated in detail. The piston member 42 is shown in an open position while the piston member 43 is shown in a closed position of operation. The piston member 42 is comprised of a cylindrical piston element 52 slidably mounted in the cylinder 38 and suitably sealed with respect to the cylinder walls. The piston element 52 has a central bore 54 to receive a valve element 53. Counterbores 55, 56 are provided in the piston element 52 above and below the central bore 54. The valve element 53 is provided with a blind bore 57 having a lower opening 58 above a plugged end 59. The plugged end 59 of valve element 53 has a flanged portion which limits upward movement of the valve element in the piston 52 element and also provides a seal in the bore 54 when engaged therewith. Spring means 60 are provided in the upper counterbore 55 to bear against a flange 61 on the upper end of the valve element 53 and maintain the valve element in its uppermost position in the position element 52. In this uppermost position, it will be appreciated that the lower opening S8 of the valve element 53 is closed relative to the counterbore 56. The flange 61 on the valve element 53 is provided with one or more radially extending grooves 62. Hence, when a piston element 52 is moved upwardly, the piston will be closed until the flange 61 (which is larger than the lower counterbore 56 of a piston element) engages the lower surface of an adjacent piston element (or wall surface) whereupon the piston element 52 is moved relative to the valve element 53 to compress the spring 60 and place the opening 53 into fluid communication with the lower counterbore 56. Fluid communication through the piston is then established through the lower counterbore 56, the port 53, bore 57 and slots 62 in a flange 61. It will be noted that the piston element is sized so that the operation of one valve element does not interfere with the operation A, gfwthe next valve element.

In "-method of the present invention, the tool is lowered to the level of interest and actuated so that the sealing pad 27a of the fluid-passage means 17 is urged into sealing contact with the casing 12 to isolate a section of the well bore 10. At this time the pre-flush fluid from the upper chamber 39 is present in the bore 2S between the closure members 29, 30, at a pressure corresponding to the pressure of the fluids 14 in the well bore 10. This pressure is indicated by pressure sensing device 36 which is transmitted via cable 16 to the surface. Detonation of the shaped/charge 24 causes a perforating jet to pass through`lhpressuri`ed1luid 14 and perforate the casing 12 and cement 13 and produce a penetration of the earth formations 11 as indicated by the dotted lines in FIG. l. By opening the closure member 233, the well fluid 14 which has entered through port (which is at a higher pressure than the formation fluids) moves piston members 44, 43, 42 to immediately supply theapre-flush fluid in chamber 39 tqfthe formations 11 until such time as the first piston member"42` engages the end wall of the cylinder 38 at which time the piston valve element 53 is operated and the second chamber 40 is discharged through piston 42 and into the perforation. In this step, the formation sands are prevented from flowing from the perforation by the pressurized plastic fluid. Subsequently, the contents of the third chamber v41 are discharged through pi's`tdns"42`,"43"when the piston 43 is opened. The pressure sensing device 36 will indicate the completion of the step by the drop in pressure when the third chamber is completely discharged. At this time, valve 35 is closed and valve 34 is opened. The opening `of VHN@ Sinergie aipoartir1..l 0f the plusaiaaud. in .the chamber 47 to be discharged into th'e'lperforation. This completes the treating operation of the tool 15 and the hydraulic system 22 is then actuated to relieve the hydraulic pressure on the pistons 19 and the valve 32 (FIG. 2) is opened so that well fluid 14 can enter through the center of the sealing pad 27a and thereby equalize the pressure across the sealing pad for easy retraction of the pad member. The tool 15 may thereafter be retrieved from the well bore 10.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Apparatus for perforating earth formations traversed by a cased well bore containing control fluids comprising: a support member, means `on said support member for sealing off a section of a well bore from contact with control iluids, said sealing off means having a normally closed central portion, means in said support member for perforating said central portion, and means for providing fluid under pressure to said central portion while it is closed so that upon operation of said perforating means the pressure within the support member is related to pressure within such sealed-off section.

2. Apparatus for perforating and treating earth formations traversed by a well bore comprising: a support member having sealing pad means for isolating a section of a well bore from contact with fluids in a well bore, said pad means having a normally closed central opening, means for perforating said closed opening, means for providing treating fluids under pressure to said closed opening before operation of said perforating means so that treating fluids can be injected immediately into such perforated section and means for providing treating fluids under pressure after operation of said perforating means so that treating fluids can be injected into such perforated section.

3. Apparatus for perforating and treating earth formations traversed by a well bore comprising: a support member having sealing pad means for isolating a section of a well bore from contact with fluids in a well bore, said pad means having a normally closed central opening, means for perforating said closed opening, first means adapted to provide rst treating fluids under pressure to said closed opening, second means adapted to provide second fluids under pressure to said central opening, and valve means selectively operable to connect or disconnect said first and second means to said central opening whereby said first fluids are provided before and after the operation of said perforating means so that treating fluids can be injected immediately into such perforated section, and said first means disconnected before said second means are connected to said central opening.

4. The apparatus of claim 3 and further including pressure sensing means coupled to said central opening.

5. A method of treating earth formations traversed by a cased borehole containing a control fluid comprising the steps of: positioning a treating uid under pressure opposite a borehole Wall section adjacent to an earth formation; isolating a space adjacent to the Wall section from contact with the control fluid in the borehole; perforating through the treating fluid and isolated wall section and into the earth formation therebeyond for releasing the treating fluid into the isolated space and for providing fluid communication from the isolated space through the isolated Wall section into a portion of the earth formation; and injecting the treating uid into the perforated earth formation.

6. A method of treating earth formations traversed by a cased borehole containing a control uid comprising the steps of: positioning a treating uid under pressure opposite a borehole Wall section adjacent to an earth formation; isolating a space adjacent to the Wall section from contact with the control fluid in the borehole; perforating through the treating Huid and isolated Wall section and into the earth formation therebeyond for releasing the treating fluid into the isolated space and for providing fluid communication from the isolated space through the Visolated wall section into a portion of the earth formation; injecting the treating fluid into the perforated earth formation; continuously measuring the pressure of the treating fluid injected; and separately injecting a pluggingand-blocking agent into the perforated earth formation.

7. A method of treating earth formations traversed by a cased borehole containing a control uid comprising the steps of 2 positioning a treating iluid under pressure opposite a borehole Wall section adjacent to an earth formation; isolating a space adjacent to the wall section from contact with the control fluid in the borehole; perforating through the treating fluid and isolated wall section and into the earth formation therebeyond for releasing the treating fluid intovthejsolated space and for providing fluid communication from the isolated space through the isolated wall section into a portion of the earth formation; injecting the treating fluid into the perforated earth formation; separately injecting a plpggipgindebloeldng agent into the perforated earth formation; and measuring the pressure applied to the plugging agent.

8. A method of treating earth formations traversed by a cased borehole containing a control uid comprising the steps of: positioning a treating fluid under pressure opposite a borehole wall section adjacent to an earth formation; isolating a space adjacent to the wall section from contact with the control uid in the borehole; perforating through the treating fluid and isolated wall section and into the earth formation therebeyond for releasing the treating fluid into the isolated space and for providing fluid communication from the isolated space through the isolated Wall section into a portion of the earth formation; injecting the treating fluid into the perforated earth formation; continuously measugingmthegpressureggfdthe treating uid, -seaafl'y'n/jecting a plugging-and-blocking agent into the perforated earth formation; and measuring the pressure applied to the plugging agent.

References Cited by the Examiner UNITED STATES PATENTS 2,457,277 12/48 Schlumberger 16655.1 2,805,722 9/57 Morgan et al. 166--35 2,842,205 7/58 Allen et al. 166-21 2,934,146 4/60 Laval 166-55 3,010,517 11/61 Lanmon 166--100 3,066,736 12/62 Venghiattis 166-55.1

CHARLES E. OCONNELL, Primary Examiner. 

5. A METHOD OF TREATING EARTH FORMATIONS TRAVERSED BY A CASED BOREHOLE CONTAINING A CONTROL FLUID COMPRISING THE STEPS OF: POSITIONING A TREATING FLUID UNDER PRESSURE OPPOSITE A BOREHOLE WALL SECTION ADJACENT TO AN EACH FORMATION; ISOLATING A SPACE ADJACENT TO THE WALL SECTION FROM CONTACT WITH THE CONTROL FLUID IN THE BOREHOLE; PERFORATING THROUGH THE TREATING FLUID AND ISOLATED WALL SECTION AND INTO THE EARTH FORMATION THEREBEYOND FOR RELEASING THE TREATING FLUID INTO THE ISOLATED SPACE AND FOR PROVIDING FLUID COMMUNICATION FROM THE ISOLATED SPACE THROUGH THE ISOLATED WALL SECTION INTO A PORTION OF THE EARTH FORMATION; AND INJECTING THE TREATING FLUID INTO THE PERFORATED EARTH FORMATION. 